Sound reproducing diaphragm



May 19, 1931. .G. G. ROCKWELL ET AL 1,806,420

SOUND REPRODUCING DIAPHRAGM Original Filed May 28, 1926 Patented May 19, 1931 UNITED STATES PATENT OFFICE GEORGE G. ELL AND CHARLES L. WALTERS, F BURY, CONNECTICUT SOUND BEPRODUCING DIAPHRAGM Application filed May 28, 1928, Serial No. 112,891. Renewed April 23, 1980.

This invention relates to sound reproducing diaphra s. One of the objects thereof is to provi e a device of the above nature which is practical and efiicient. Another ohject is to provide a diaphragm which iscapable of g1ving a more natural, fuller and truer reproduction ,of sounds than is accomplished by sound reproducing diaphragms commonly in use. Another object is to provide a diaphragm of the above nature which is simple in construction and which ma be manufactured at low cost. Other ob ects will be in part obvious or in part pointed out hereinafter.

i The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts as will be exemplified in the structure to be hereinafter described and the scope of the a plica- 2 tion of which will be indicated in the ollowing claims. v

n the accompanying drawingsin which are shown one or more of the various possible embodiments of this invention,

Figure 1 is asectional view of one form of the diaphragm associated with the stylus ofaphonograp Figure 2 is a sectional view showing a modified form of the diaphragm mounted in operative relation to an electromagnet such as employed, for example, in radio loud speakers, and i Fi re 3 is a front elevation of'a portion of I the iaphragm shown in Figurej2;

Referrin now'to Figure 1 of the drawings, the dlaphragm shown therein is in the form of a solid disk which is preferably circular. The diaphragm is secured about its periphery in-a casing 10 which represents the usualsound box of a sound reproducing machine or phonograph. Attached to the center of the diaphragm by a screw 11 passing therethrough is the usual stylus arm 12 which is pivoted to the casing at 13 and carries at its lower end the needle or stylus 14. It will be understood; of course, that the needle 14 coacts with the grooves in a rotatmg record, imparting: vibrations to-the arm 12 which% inturnvibrates the diaphragm to efi'ect reproduetion of i I Considerin now the construction of this diaphragm s own in Figure 1, it is preferably one solid member and made of .a suitable resilient or flexible material such, for example, as hard rubber or the like. The central portion of the diaphragm to which the stylus arm 12 is attached is thin, and immedi- These heav rings 16 are joined together by thin, web-1i e rings 17.

Since each of the heavy rings is of greater diameter than the next adjacent inner ring, 7 each of the rings 16 is of greater size and hence of greater weight than the next adj acent inner heavy ring. Thus, the heavy rings '16 increase progressively in weight from the center outwardly, each of the heavy rings 76 constituting a member which is heavier than its nei hboring heavy ring on the inner side thereo It may be noted that the thickness of the rings 16 in an axial direction is substantially greater than the thickness of the an ordinary diaphragm.

A diaphragm constructed as above described. gives a fuller and richer tone than does the ordinary diaphragm. There are provided in effect, by this construction,.a as series of independent dia hragms each of which is best suited to vi rate for the reproduction of sounds contained within a certain range of pitch. For example, the notes of very highest pitch do not require the vibration of a large or hea body for their proper reproduction and. once they may be reproduced by vibrations of the thin central portion of this diaphragm. The notes of next lowest pitch may be reproduced by vibration only of the portion ,of the diaphragm taking in the thin central portion andth'e first heavy ring 16. The notes of next lower pitch may be reproduced by vi bration of that portion of the diaphragm 1 diaphragm shown in Figure 2 is of a suitable non-magnetic material such, for example, as

hard rubber. At the center thereof is secured a small disk 21 of magnetic material, preferably metal, which is positioned to be attracted by the electromagnet. Variations in the electric current passed through the coil of the magnet efiect' variations in the pull of the magnet upon the disk 21 thereby causing a vibratory movement of the disk 21, which vibrations are transmitted-to the diaphragm. The disk 21 is secured to the -diaphra proper by a suitable rivet 21a or. the li e which forms the only support for the disk 21 and the only connection between the disk 21 and the non-magnetic material of the diaphragm. The main body of the diaphragm is secured about its periphery in the casing-l8.

- In this dia hra of Figure 2, the central portion 20t ereo to which the disk 21 is secured, is thin as is the central portion of the diaphragm shown in Figure l, and this portion increases gradually in thickness 'in a radial direction. About the central portion 20 the diaphragm consists of a series of concentric rings 22 which are spaced radially and connected by thin web-like rings 23. The thin rings 23 donot all lie in the same I plane but they are 7 preferably staggered as shown so that no two adjacent rin 23 lie in the same plane. In addition, 'as s own in Fi re 2and in Figure 3, it is advantageous to ave the heavy rings 22 increase progressively in cross-sectional area from the center outwardly. This increase in the cross-sectional area of the rings increases the difierence in weight between adjacent rings. The vibrations of the diaphragm shown in Fi ure 2 in response to sounds of various pits; are substantially as described inconnection with the diaphragm of Figure 1.

Although hard rubber or the like is found to be a satisfactory material for the constructlon of these diaphragms, it is to be under- 7 stood that other materials ma be employed.

The diaphragms may be D8 0 conveniently by cutting away the required rtions from a solid disk of material, sim cutting circular grooves in the material rom op to surfaces of the disk to form the thin we -,like portions or rings 17 or 23.

As man possible embodiments may be 06 made of t e above invention and as. many preted as illustrative and not a limiting sense.

We& claim as our (irdiventionii h 1. soun repr ucing 'a r prisin a disk made up of a seri ds o l r dially spacef concentric rings of substantial thickness in an axial direction joined together by intervening web-like rin of a thickness in an axial direction substantially less than that of said first rings.

2. A sound reproducing diaphragm comprising a thin central portion and about said central portion a series of spaced concentric rings which are thicker in an axial direction than is said central portion, said spaced concentric rings being joined together by thin web-like rings.

3. A sound reproducing diaphragm comprising a disk which has a small central portion thereof gradually increasing in thickness in a radial direction from its center, a ring about said small central portion which is relatively thick in an axial direction, and

com-

spaced radially from said first thick ring a series of similar relatively thick rings spaced from each other'pin a radial direction and joined by rings which are relatively thin in an axial direction. 7

4. A sound reproducing diaphragm com prising a disk made up of a series of radially spaced concentric rings of substantial crosssectional area and weight joined together by thin and web-like intervening rings, said first rings increasing progressivelyin crosssectional area and weight from the central portion of said disk outwardly toward the periphery.

5. A sound reproducing diaphra comprising a disk made up of a. series 0 radially spaced concentric rings of substantial thickness in an axial direction joined together by intervening web-like rings of a thickness in an axial direction substantially less than that of said first rings, the adjacent web-like rings lying in different planes.

6. An acoustic diaphragm comprising a disk-like member made up of radially aced substantially concentric rings each 0 substantially rectangular cross-section and intervening relatively thin web-like rings joinin said first-mentioned rings together.

An acoustic diaphragm com rising a disk-like member of substantial thickness in an axial direction and having pairs of concentric grooves, the grooves of each pair being on opposite sides of said member and of su stantlallg the same diameter and separated from eac other by thin web-like portions.

3. An acoustic diaphragm compri a disk-like member of substantial thickness in an axial direction and having pairs of concentric grooves, the grooves of each pair being on opposite sides of said member and one groove of each pair being of greater depth than the other groove.

9. An acoustic diaphragm comprising a member made up of a series of spaced rings grouped about a common axis, said rings being of progressively diifering diameters and having different natural periods of vibration, and means joining adjacent spaced rings, said joining means eing of a character to give said rings freedom to vibrate relative to each other.

10. An acoustic diaphragm comprising a member made up of a series of concentric ring-like members, each of substantial mass,

. said rings having different natural periods of vibration and having difierent diameters, and means holding said rings concentrically and joining said rings, said holding and joining means being of a thickness insuflicient to prevent said rings to vibrate relative to each other.

'11. An acoustic diaphragm comprising a member made up of a series of concentric ring-like members, each of substantial mass, said rings having different natural periods of vibration and having different diameters, and means holding said rings concentrically and joining said rings, said holding and joining means being of a thickness insuflicient to prevent said rings to vibrate relative to each other and extending in a general radial direction between adjacent rings.

12. An acoustic diaphragm comprising a member made up of a series of concentric ring-like members, each of substantial mass, said rings having different natural periods of vibration and having different diameters, and means holding said rings concentrically and joining said rings, said holding and joining means being of a thickness insufiicient to prevent said rings to vibrate relative to each other, said rings and the joining means intermediate of adjacent rings being integral. In testimony whereof, we have signed our names to this specification this nineteenth day of May, 1926. ,4

GEORGE G. ROCKWELL. CHARLES L. WALTERS. 

